In general, the vertebral column usually consists of 24 vertebrae (except for sacral vertebrae), and the vertebrae are connected through joints. Disks are placed between the joints for absorbing impacts and supporting loads when a human body moves or the joints move.
The vertebral column has an important function of not only supporting postures of the human body while absorbing impacts, but also protecting all organs in the body while supporting the motion of the human body.
However, if the vertebral column is injured or curved due to external and artificial causes, degenerative factors, or abnormal postures that continue for a long period of time, the vertebral column compresses the spinal cord passing through the spinal canal, which causes severe pain.
That is, a patient with the partially damaged vertebral column cannot perform activity required for personal life. Even in a case in which the vertebral column is not severely damaged, the damaged site of the vertebral column is pressed by or brought into contact with other adjacent parts, which causes pain.
A spinal complex cage, which is used for fusion which is one of the methods for surgically treating spinal diseases, is an implant that is implanted between upper and lower vertebral bodies after removing a damaged disc in order to assist bone grafting for lumbar vertebrae, treatments for spondylolisthesis, and fusion for spondylolisthesis and scoliosis. The spinal complex cage for an intervertebral body is used for a treatment of structural abnormalities such as degenerative lumbar herniated intervertebral discs, bone grafting for the vertebral column, fusion for spondylolisthesis and scoliosis, restoration of vertebral bodies in spondylolisthesis, restoration of heights of fractured vertebral bodies, and the like.
In the related art, the spinal complex cage for an intervertebral body is made of polyether ether ketone (PEEK). Because the PEEK material is a radiotransparent material, the spinal complex cage for an intervertebral body has been used while a titanium marker is inserted into a cage in order to ascertain a position of the cage in the computed tomography (CT).
However, the PEEK material is often damaged when the PEEK material is inserted between the vertebral bodies, and it is difficult to ascertain the exact position of the cage by means of the titanium marker.
The spinal complex cage for an intervertebral body made of titanium often deforms the vertebral bodies after surgery or causes subsidence into the vertebral bodies because of a high elastic modulus, which causes problems such as re-fracture or separation. Further, radiation cannot penetrate the spinal complex cage for an intervertebral body, which makes it difficult to determine spinal fusion in the CT.
To solve the aforementioned problems in the related art, Korean Patent No. 10-1370424 discloses a “spinal composite implant” which includes a cage which is made of resin, and a metal layer which is made of porous metal and attached to an outer surface of the cage.
The related art uses the resin cage and the metal layer and somewhat solves the aforementioned problems. However, the metal layer is attached to the resin cage by thermo-compression bonding, such that the manufacturing method is complicated. Further, because the spinal composite implant has a fixed size and a fixed shape, the spinal composite implant cannot be quickly applied in accordance with shapes and intervals between the vertebral bodies between which the spinal composite implant is to be inserted, which makes it difficult to accurately and precisely perform the surgical operation.
Because the metal layer is formed in a flat plate shape, the spinal composite implant cannot be securely fixed between the vertebral bodies, and there is a concern that the spinal composite implant is moved out of a position where the spinal composite implant is initially implanted, which causes deterioration in accuracy of the surgical operation.